JTAG-HS3 Programming Cable with Xilinx Zynq 3.3V

[Amjad]

Hello

I'm using Digilent JTAG-HS3 Programming Cable with a Zynq 7000 based board. With HS3, I'm able to program the PL of the Zynq using Vivado 2016.4.

In my application, I need to have an extension cable connection the Zynq to the HS3; this extension cable is about 1m long.

In case I set the reference voltage on the base board to 2.5V, I'm able to connect to the Zynq, program it and flash the QSPI memory. On the other hand, if I change the reference voltage on the base board to 3.3V, I'm not able to detect the Zynq at all.
In Vivado, I obtain the error message:
ERROR: [Labtools 27-2269] No devices detected on target localhost:3121/xilinx_tcf/Digilent/210299A1F0C9.

Are there any specific requirements to make the extension cable work with HS3 and Zynq using 3.3 reference voltage?

[jpeyron]

Hi @Amjad,

The JTAG-HS3 module wasn’t designed to be connected with such a long cable. In fact, it was designed to plug directly into the target board, which is why we used the standard 14-pin Xilinx JTAG header. I’d expect it to work with shorter cables (<12”) but a meter is really long. I think that the cable is adding too much impedance and that the timing of the TMS, TDI, and TDO signals with respect to TCK probably isn’t being met. You could try running it at a slower clock frequency to see if that improves anything.

cheers,

Jon